Photographic products containing polytetrafluoroethylene layer



March 15, 1966 R. P. COOK 3,240,604

PHOTOGRAPHIC PRODUCTS CONTAINING POLYTETRAFLUOROETHYLENE LAYER FiledFeb. 18, 1965 PHOTOGRAPHIC sILvER HALIDE GELATIN 1 j W EMULSION LAYER k\SUPPORT LAYER POLYTETRAFLUOROETHYLENE CONTAINING GELATIN LAYER IPOLYTETRAFLUOROETHYLENE LAYER FIG. I

BLUE SENSITIVE SILVER HALIDE GELATIN EMULSION LAYER YELLOW DYE DEVELOPERCONTAINING /GELATIN LAYER 6 I GREEN SENSITIVE SILVER HALIDE GELATINEMULSION LAYER 8 r IvIAGENTA DYE DEvELOPER CONTAINING GELATIN LAYER \REDSENSITIVE SILVER HALIDE GELATIN IO EMULSION LAYER 2 ?\\CYAN DYEDEVELOPER CONTAINING GELATIN LAYER SUPPORT LAYER POLYTETRAFLUOROETHYLENECONTAINING GELATIN LAYER FIG. 2

INVfJTZR. MMW

ATTORNEYS United States Patent 3,240,604 PHOTOGRAPHIC PRODUCTSCONTAINING POLYTETRAFLUOROETHYLENE LAYER Russell ll. Cools, Sudbury,Mass., assignor to Polaroid Corporation, Cambridge, Mass., a corporationof Delaware Filed Feb. 18, 1963, Ser. No. 259,084 1 Claim. (Cl. 96-73)This invention relates to photographic elements and, more particularly,to composite photographic elements which comprise a plurality of layers,including a support layer, a silver halide gelatin emulsion layer on oneside of said support layer, and a polytetrafluoroethylene containinglayer located as an external layer of said plurality of layers.

Under conditions of general commercial employment, compositephotographic film elements are stored as packaged film rolls or filmpacks for periods of months prior to their actual use. During suchstorage, the sheet material is under varying parameters of compressivepressures and, in addition, may be subjected to a wide variety ofenvironmental stresses or extremes, as, for example, varying temperatureconditions and relative humidities.

In that the film rolls and film packs must maintain a high degree ofefiiciency and reliability during storage, the component sheet materialsmust be prevented from interactions which would affect their structuralintegrity or dimensional stability, whereby their ultimate photographicemployment would be impaired.

In particular, photographic film elements which comprise a support orfilm base having one or more gelatin layers coated on one or both sidesof the support must be prevented from adhering or blocking when stacked,for example, gelatin layer contacting gelatin or other polymeric layer,in a film pack, or when a gelatin layer containing sheet film is rolledupon itself, as occurs in roll film.

In the past, such adhesion or blocking has been prevented, in general,by the addition of relatively large amounts of conventional gelatinhardening agents, as, for example, inorganic agents providing polyvalentmetallic atoms, especially polyvalent aluminum or chromium ions, forexample, potash alum [K Al (SO -24H O] and chrome alum [K Cr (SO -24HO], and organic agents of the aldehyde type such as formaldehyde,glyoxal, mucochloric acid, etc., the ketone type such as diacetyl, thequinone type, etc., to a gelatin layer positioned such as to be subjectto blocking.

The use of the last-mentioned relatively large amounts of such hardeningagents gives rise to a serious problem of controlling the disposition ofsuch agents, so as to insure that they do not migrate from the layer inwhich they are deposited and deleteriously contaminate a photosensitivesilver halide gelatin layer of the film unit.

Objects of the present invention are therefore to provide photographicfilms which include at least one gelatin containing layer and areparticularly adapted to alleviate blocking during storage of same.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the product possessing the features,properties and the relation of components which are exemplified in thefollowing detailed disclosure, and the scope of the application of whichwill be indicated in the claims.

For the fuller understanding of the nature and objects of the invention,reference should be had to the following detailed description taken inconnection with the accompanying drawing wherein:

FIGURE 1 is a diagrammatic fragmentary cross-secice tional view of aphotographic film product of the present invention particularly adaptedfor employment in monochromatic photographic processes; and

FIG. 2 is a diagrammatic fragmentary cross-sectional View, similar toFIGURE 1, and illustrates a photographic element of the presentinvention particularly adapted for employment in multichromaticphotographic processes.

It has now been found that blocking, which is especially serious whenfilm units, stored as previously noted, attain temperatures above 85 F.and relative humidities above may be prevented by locating a layercomprising polytetrafluorethylene as an external layer of the film unit.

The polytetrafluorethylene containing layer may be located as the distallayer on either or both sides of the support and may additionallycontain one or more polymeric film-forming components such as gelatin,one or more modifying agents such as hardening agents, plasticizers,etc., for such components, and one or more coating aids to facilitatefabrication of the layer.

Preferably the polytetrafiuoroethylene containing layer is located onthe support on the side opposite the photosensitive strata and may bethere deposited by conventional coating techniques adapted to distributea coating solution comprising a dispersion of discrete polytetrafluoroethylene granules, preferably of colloidal size and dispersed in apolymeric film-forming solution.

For purposes of simpilicity, an aqueous coating solution is preferredalthough it will be readily recognized that an organic coating system,for example, a system employing one or more liquid hydrocarbons as thesolvent, or a coating system utilizing a coating solution containingdispersed aqueous and organic phases, may also be employed wheredesired.

In a preferred embodiment, the concentration of polytetrafiuoroethylenepresent falls within the range of about 0.05 to 10 partspolytetrafluoroethylene per part of polymeric film-forming resin, byweight.

The polymeric film-forming component of the preferred coating solutionmay be a synthetically derived thermoplastic polymer such aspoly-4-vinyl pyridine which may be coated from an acetic acid-watersystem, cellulose nitrate which may be coated from an ethyl acetatesystem, cellulose acetate butyrate which may also be coated from anethyl acetate system, a mixture of such polymers, for example,poly-4-vinyl pyridine in acetic acid and water in combination withcellulose nitrate in ethyl acetate, etc., or one of the naturallyoccurring filmforming polymers such as gelatin, casein, etc.

Where desired, one or more conventional coating aids such as saponin,etc., and/or conventional polymeric modifiers, for example, plasticizerssuch as glycerine, glycols, sorbitol, etc., hardeners such as thosepreviously enumerated, etc., may be included in the coating compositionto facilitate the selected coating process employed and to providedesired properties to the resultant polymeric film. It will berecognized that the specific choice of addenda is extremely broad andwill be determined, in part, by the polymeric resin employed, theconditions of coating, and the physical and chemical properties desiredof the resultant film.

FIGURE 1 of the accompanying drawing illustrates a compositephotographic element which comprises a support layer 2, a photographicsilver halide gelatin emulsion layer 1 located on one surface of supportlayer 2, a polytetrafluoroethylene containing gelatin layer 3 located onthe opposite surface of support layer 2, and a polytetrafiuoroethylenelayer 4 located on the surface of layer 3 located distal to supportlayer 2.

A multilayer subtractive multicolor film unit particularly adapted foruse in the photographic processes of US. Patent No. 2,983,606, issuedMay 9, 1961, and the copending US. application of Edwin H. Land andHoward G. Rogers, Serial No. 565,135, filed February 13, 1956, isillustrated in FIG. 2, of the accompanying drawing. The illustratedphotosensitive element comprises: a support layer 2, a gelatin layercontaining cyan dye developer, a red-sensitive silver halide gelatinemulsion layer 9, a gelatin layer 8 containing magenta dye developer, agreen-sensitive silver halide gelatin emulsion layer 7, a gelatin layer6 containing yellow dye developer, and a blue-sensitive silver halidegelatin emulsion layer 5, mounted on one surface of support layer 2, anda gelatin layer 3 containing polytetrafluoroethylene and, preferably,additionally containing a gelatin hardening agent, mounted on theopposite surface of support layer 2.

The invention will be illustrated in greater detail in conjunction withthe following specific examples which set out representative utilizationof the novel concepts of this invention, which, however, are not limitedto the details therein set forth and are intended to be illustrativeonly.

EXAMPLE 1 1.33 mls. of an aqueous polyetetrafluoroethylene dispersion(sold by E. I. du Pont de Nemours & Co., Wilmington, Delaware, under thetrade designation Teflon T-30 and comprising an aqueous dispersioncontaining approximately 60% polytetrafluoroethylene, by weight), wasadded to 80 mls. of a 10% gelatin solution, at 65 C. To this mixture wasadded 10 mls. of an aqueous 3% solution of oxidized starch sold by MilesChemical Company, Clifton, New Jersey, under the trade designationSumstar 190.

The final mixture contained 8.9% gelatin, 0.89% polytetrafiuoroethyleneand 0.33% oxidized starch, by weight, and was coated immediately on thecellulose acetate film base surface of a multicolor photographic film ofthe type described in explanation of FIG. 2.

In general, the photosensitive film unit comprised a cellulose acetatefilm base or support carrying a redsensitive silver halide gelatinemulsion stratum, a greensensitive silver halide gelatin emulsionstratum and a blue-sensitive silver halide gelatin emulsion stratum;said emulsions having dispersed in water-immiscible organic solvents andcontained in separate alkali-permeable gelatin layers behind theemulsion strata, respectively, a cyan dye developer, a magenta dyedeveloper and a yellow dye developer. The particular dye developersemployed in the photosensitive elements were1,4-bis-(a-methyl-B-hydroquinonyl-ethylamino)-5,S-dihydroxyanthraquinone(a cyan dye developer); 2-(p-[2',5-dihydroxyphenethyl]-phenylazo)-4-isopropoxy-l-naphthol (a magenta dye developer); and1-phenyl-3-n-hexyl-carboxamido-4-(p-[hydroquinonylethyl]-phenylaZo)-4-pyrazolone(a yellow dye developer). The last-mentioned yellow and magenta dyedevelopers are disclosed in the copending US. application of Blout etal., Serial No. 145,978, filed October 18, 1961 and the cyan dyedeveloper is disclosed in the copending US. application of Blout et al.,Serial No. 233,461, filed October 26, 1962, now US. Patent No.3,135,606.

A film unit prepared as set forth above, and a control film unitprepared as set forth above except that the polytetrafluoroethylenecomponent was omitted, were stored in roll form at 100 F. and 90%relative humidity for 16 hours.

The control roll blocked so severely as to be incapable of beingunrolled without substantial destruction of the film units structuralintegrity and photographic utility while the polytetrafluoroethylenecontaining film unit exhibited no blocking and no impairment of itsphotographic utility.

As examples of additional formulations, for employment in the generalprocedure of Example I, mention may be made of:

Aqueous dispersion of polytetrafluoroethylene (sold under the trade nameTeflon TD 3 by E. I. du Pont de Nemours & Co., Wilmington,

Delaware) cc 5.0 Tween 20 (trade name of Atlas Powder Company,

Wilmington, Delaware, for a nonionic surfaceactive emulsifying agentcomprising complex esters of fatty acids and polyhydric materials) cc3.0 One-half sec. cellulose nitrate g 16.6 Ethyl acetate cc 75.4

Aqueous dispersion of polytetrafluoroethylene (TD 3) cc 1.50Poly-4-vinylpyridine g 2.3 Glacial acetic acid cc 2.35 Water cc 93.80

One-half sec. cellulose nitrate g 4.24 Ethyl acetate cc 19.20Poly-4-vinylpyridine g 1.68 Glacial acetic acid cc 1.68 Water cc 69.10Aqueous dispersion of polytetrafluoroethylene (TD 3) cc 2.76 Tween 20 cc1.34

Photosensitive elements prepared, employing each of the aforementionedcompositions, respectively, exhibit substantially no blocking and/orimpairment of their photographic utility, when subjected to the testprocedures of the preceding example.

EXAMPLE 2 A photosensitive film unit containing the plurality ofassociated photosensitive silver halide gelatin layers and dye developercontaining gelatin layers detailed in Example 1 on one surface and agelatin layer on the opposite surface of the film base, was coated withan aqueous dispersion of polytetrafluoroethylene deposited on theexternal surface of the last-mentioned gelatin layer in a concentrationof 10-15 mgs. of solids per square foot.

The film unit was then stored in roll form at 100 F. and 90% relativehumidity for 16 hours and exhibited no blocking and/ or impairment ofits photographic utility.

EXAMPLE 3 The procedure of Example 2 was repeated except that theaqueous polytetrafluoroethylene dispersion was coated on the externalsurface of the film units blue-sensitive silver halide gelatin emulsionlayer.

EXAMPLE 4 10 mls. of Teflon T-30 was added, at 20 C., to mls. of a 10%gelatin solution. To this mixture was added 4 mls. of a 5% mucochloricacid solution.

The final mixture contained 10.6% gelatin, 6.4% polytetrafluoroethylene,and 0.21% mucochloric acid, by weight, and was coated on the celluloseacetate film base of a multicolor photographic film unit of the typedescribed in Example 1, at a thickness of 17 microns.

3.5 mls. of Teflon T30 was then mixed with 80 mls. of a 2.5% gelatinsolution, at 65 C.

The mixture contained 2.4% gelatin and 2.5% polytetrafluoroethylene, byweight, and was coated as the external layer of the plurality ofassociated photosensitive emulsion and dye containing gelatin layers, ata thickness of 5 microns.

Subjection of the film units of Examples 3 and 4 to the test procedureof Example 2 provided substantially identical results. Furthermore, noloss of acuity, speed, or dye transfer is observed when the film unitsare employed in the diffusion transfer photographic processes of theaforementioned US. Patent No. 2,983,606 and application Serial No.565,135.

It will be recognized that the polymeric layers formulated in accordancewith the instant disclosure, e.g., the polytetrafluoroethylenecontaining gelatin layers of the examples, may additionally containvarious addenda such as, for example, silver halide developing agents.

Employment of film units, prepared in accordance with the aforementionedexamples, in photographic film packs, for example, of the type disclosedin US. Patent No. 3,002,437, issued October 3, 1961, and subjecting themto the environmental conditions previously described provides resultsanalogous to those described with reference to roll film testing.

In general, such film packs comprise an envelope or magazine containinga plurality of photographic elements or films adapted to be withdrawntherefrom, singularly, and in a predetermined sequence. As disclosed inthe last-stated US. patent, such photographic elements may comprise anassemblage including a first photosensitive sheet element adapted to beexposed and placed in superposed relationship with a second sheetelement adapted to receive a photographic diffusion transfer image andprocessed by a suitable processing composition included in theassemblage.

It has quite unexpectedly been found that a gelatin layer containingpolytetrafluoroethylene absorbs considerably less water, for example, inthe order of one-half or less the normal amount of absorbed water,depending upon the concentration of polytetrafiuoroethylene, than isabsorbed by such layer in the absence of the polytetrafiuoroethylene,when stored at 90% relative humidity and 100 F. for approximately 48hours. This increase in the water resistancy characteristics of agelatin layer containing polytetrafiuoroethylene may be postulated to bethe result of a hardening action for which no logical explanation yetappears.

Since certain changes may be made in the above product without departingfrom the scope of the invention herein involved, it is intended that allmatter contained in the above description or shown in the accompanyingdrawing shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:

A photographic prod-uct which comprises a plurality of layers includinga support layer, located on one surface of said support layer a cyan dyedeveloper-containing gelatin layer, a red-sensitive silver halidegelatin emulsion layer, a magenta dye developer-containing gelatinlayer, a green-sensitive silver halide gelatin emulsion layer, a yellowdye developer-containing gelatin layer, and a blue-sensitive silverhalide gelatin emulsion layer, and located on the opposite surface ofsaid support layer a gelatin layer containing discretepolytetrafluoroethylene granules present in a concentration within therange of 0.05 to 10 parts polytetrafluoroethylene per part of gelatin.

References Cited by the Examiner UNITED STATES PATENTS 2,322,037 6/ 1943Lindquist 96-94 2,495,111 1/1950 Land 96-76 X 2,876,131 3/1959 Kumnicket a1 26092.1 3,077,400 2/1963 Rogers et al 96---73 X 3,146,102 8/1964Weyerts et al 963 FOREIGN PATENTS 718,232 11/1954 Great Britain.

NORMAN G. TORCHIN, Primary Examiner.

